Driving circuit

ABSTRACT

A driving circuit includes a driving transistor, a capacitor, a reset circuit, a touch sensing electrode, a sensing circuit, and a read circuit. The capacitor is electrically coupled to a gate terminal of the driving transistor. The reset circuit is electrically coupled to the gate terminal of the driving transistor, and the reset circuit is configured to reset the voltage level of the gate terminal of the driving transistor. The sensing circuit is electrically coupled between the touch sensing electrode and the gate terminal of the driving transistor, and the sensing circuit is configured to transmit the voltage level of the touch sensing electrode to the gate terminal of the driving transistor. The read circuit is electrically coupled to the driving transistor, and the read circuit is configured to output a touch sensing signal according to the voltage level of the gate terminal of the driving transistor.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwan Application Serial Number110120830, filed Jun. 8, 2021, which is herein incorporated by referencein its entirety.

BACKGROUND Field of Invention

The present invention relates to a driving circuit. More particularly,the present invention relates to a driving circuit with light emittingelement and touch sensing function.

Description of Related Art

In today's technology, display panels with touch sensing functions areoften composed of independent touch sensing circuits and pixel circuits.However, since some touch sensing elements (for example, optical touchsensing elements) are easily affected by ambient light and panelstructure, their sensitivity is usually reduced in order to reduce thenoise received during touch sensing, the display time of the displaypanel is usually reduced. Moreover, under such respective operatingcircuit architectures, additional independent touch sensing time must bedivided, which will cause the charging rate of the touch sensing elementand the resolution of the touch sensing function to be limited.

SUMMARY

The invention provides a driving circuit. The driving circuit comprisesthe driving transistor, the capacitor, the reset circuit, the touchsensing electrode, the sensing circuit, and the read circuit. Thecapacitor is electrically coupled to the gate terminal of the drivingtransistor. The reset circuit is electrically coupled to the gateterminal of the driving transistor, and configured to reset the electricpotential of the gate terminal of the driving transistor. The sensingcircuit is electrically coupled between the touch sensing electrode andthe gate terminal of the driving transistor, the sensing circuit isconfigured to transmit the electric potential of the touch sensingelectrode to the gate terminal of the driving transistor. The readcircuit is electrically coupled to the driving transistor, and the readcircuit is configured to output the touch sensing signal according tothe electric potential of the gate terminal of the driving transistor.

In summary, the present disclosure uses the touch sensing electrode tosense the user's touch, and uses the sensing circuit to transmit theelectric potential of the touch sensing electrode to the gate terminalof the driving transistor, then the read circuit outputs the touchsensing signal according to the electric potential of the gate terminalof the driving transistor, so that the driving transistor can integratethe touch sensing function and the function of the pixel drivingtransistor.

It is to be understood that both the foregoing general description andthe following detailed description are by examples, and are intended toprovide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by read the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows:

FIG. 1A shows a function block diagram of the driving circuit accordingto some embodiment of the present disclosure.

FIG. 1B shows a circuit architecture diagram of the driving circuit inFIG. 1A according to some embodiment of the present disclosure.

FIG. 2A shows a function block diagram of the driving circuit accordingto some embodiment of the present disclosure.

FIG. 2B shows a circuit architecture diagram of the driving circuit inFIG. 2A according to some embodiment of the present disclosure.

FIG. 3 is a timing diagram of the control signals of the driving circuitin

FIG. 2B according to an embodiment.

FIG. 4A is a circuit state diagram of the driving circuit in FIG. 2Bduring the reset period P1.

FIG. 4B is a circuit state diagram of the driving circuit in FIG. 2Bduring the sensing period P2.

FIG. 4C is a circuit state diagram of the driving circuit in FIG. 2Bduring the compensation period P4.

FIG. 4D is a circuit state diagram of the driving circuit in FIG. 2Bduring the writing period P5.

FIG. 4E is a circuit state diagram of the driving circuit in FIG. 2Bduring the emitting light period P6.

FIG. 5 is a schematic diagram of the structure of the touch sensingelectrode in the thin film transistor layer in FIG. 2A and FIG. 2B.

FIG. 6A shows a function block diagram of the driving circuit accordingto some embodiment of the present disclosure.

FIG. 6B shows the circuit architecture diagram of the driving circuit inFIG. 6A according to some embodiment of the present disclosure.

FIG. 7A is a circuit state diagram of the driving circuit in FIG. 6Bduring the reset period P1.

FIG. 7B is a circuit state diagram of the driving circuit in FIG. 6Bduring the sensing period P2.

FIG. 7C is a circuit state diagram of the driving circuit in FIG. 6Bduring the compensation period P4.

FIG. 7D is a circuit state diagram of the driving circuit in FIG. 6Bduring the writing period P5.

FIG. 7E is a circuit state diagram of the driving circuit in FIG. 6Bduring the emitting light period P6.

FIG. 8 is a waveform diagram of the control signal of the drivingcircuit and the current flowing through the driving transistor in FIG.6B.

DETAILED DESCRIPTION

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

FIG. 1A shows a function block diagram of a driving circuit 100 aaccording to some embodiment of the present disclosure. As shown in FIG.1A, the driving circuit 100 a includes a touch sensing electrode TP, areset circuit 110, a sensing circuit 120, a read circuit 130, acapacitor Cs, and a driving transistor Td.

In terms of architecture, the capacitor Cs is electrically coupled tothe gate terminal of the driving transistor Td. The reset circuit 110 iselectrically coupled to the gate terminal of the driving transistor Td,the reset circuit 110 is used to reset the electric potential of thegate terminal of the driving transistor Td. The sensing circuit 120 iselectrically coupled between the touch sensing electrode TP and the gateterminal of the driving transistor Td, the sensing circuit 120 is usedto transmit the electric potential of the touch sensing electrode TP tothe gate terminal of the driving transistor Td.

The driving transistor Td is electrically coupled between the firstsystem voltage terminal VDD and the read circuit 130. The first terminalof the driving transistor Td is electrically coupled to the first systemvoltage terminal VDD. The read circuit 130 is electrically coupled tothe second terminal of the driving transistor Td, and the read circuit130 is used to output the touch sensing signal TS according to theelectric potential of the gate terminal of the driving transistor Td.

Please refer to FIG. 1B, FIG. 1B shows a circuit architecture diagram ofthe driving circuit 100 a in FIG. 1A according to some embodiment of thepresent disclosure.

As shown in FIG. 1B, the reset circuit 110 includes the first transistorT1, the second transistor T2, and the third transistor T3. The firstterminal of the first transistor T1 is electrically coupled to the firstterminal of the capacitor Cs and the gate terminal of the drivingtransistor Td, the second terminal of the first transistor T1 iselectrically coupled to the reference voltage terminal Vref, and thegate terminal of the first transistor T1 is used to receive the firstcontrol signal RST(n). The first terminal of the second transistor T2 iselectrically coupled to the second terminal of the capacitor Cs, thesecond terminal of the second transistor T2 is electrically coupled tothe reference voltage terminal Vref, and the gate terminal of the secondtransistor T2 is used to receive the first control signal RST(n). Thefirst terminal of the third transistor T3 is electrically coupled to thetouch sensing electrode TP, the second terminal of the third transistorT3 is electrically coupled to the second terminal of the capacitor Cs,and the gate terminal of the third transistor T3 is used to receive thefirst control signal RST(n).

The sensing circuit 120 includes the fourth transistor T4. The firstterminal of the fourth transistor T4 is electrically coupled to thetouch sensing electrode TP, the second terminal of the fourthtransistorT4 is electrically coupled to the first terminal of thecapacitor Cs and the gate terminal of the driving transistor Td, and thegate terminal of the fourth transistor T4 is used to receive the secondcontrol signal SC(n).

The read circuit 130 includes the fifth transistor T5. The firstterminal of the fifth transistor T5 is electrically coupled to thesecond terminal of the driving transistor Td, the second terminal of thefifth transistor T5 is used to output the touch sensing signal TS, andthe gate terminal of the fifth transistor T5 is used to receive thesecond control signal SC(n).

In operation, firstly, by controlling the logic level of the firstcontrol signal RST(n), the electric potential of the reference voltageterminal Vref can be respectively transmitted to the gate terminal ofthe driving transistor Td and the touch sensing electrode TP through thefirst transistor T1 and the third transistor T3, and reset the gateterminal of the driving transistor Td and the electric potential of thetouch sensing electrode TP. Then, by controlling the logic level of thesecond control signal SC(n), the electric potential of the touch sensingelectrode TP can be transmitted to the gate terminal of the drivingtransistor Td through the fourth transistor T4. In this way, the drivingtransistor Td outputs the touch sensing signal TS through the fifthtransistor T5 according to the electric potential of gate terminal ofthe driving transistor, thereby performing touch sensing.

Please refer to FIG. 2A, FIG. 2A shows a function block diagram of thedriving circuit 100 b according to some embodiment of the presentdisclosure. As shown in FIG. 2A, the driving circuit 100 b includes thetouch sensing electrode TP, the reset circuit 110, the sensing circuit120, the read circuit 130, the capacitor Cs, and the driving transistorTd.

The connection relationship and operation method of the touch sensingelectrode TP, the reset circuit 110, the sensing circuit 120, the readcircuit 130, the capacitor Cs, and the driving transistor Td of thedriving circuit 100 b of FIG. 2A are respectively similar to theconnection relationship and operation method of the touch sensingelectrode TP, the reset circuit 110, the sensing circuit 120, the readcircuit 130, the capacitor Cs, and the driving transistor Td of FIG. 1A.Therefore, it will not repeat here.

The driving circuit 100 b further includes the compensating circuit 140,the voltage stabilizing circuit 150, the writing circuit 160, and thelight emitting element L1. In some embodiment, the light emittingelement L1 can be implemented by micro light emitting diodes, lightemitting diodes, mini light emitting diodes, or other light emittingelements.

On the structure, the driving transistor Td and the light emittingelement L1 are electrically connected in series between the first systemvoltage terminal VDD and the second system voltage terminal VSS. Indetail, the first terminal of the driving transistor Td is electricallycoupled to the first system voltage terminal VDD, the second terminal ofthe driving transistor Td is electrically coupled to the first terminalof the ninth transistor T9, the second terminal of the ninth transistorT9 is electrically coupled to the first terminal of the light emittingelement L1, the gate terminal of the ninth transistor T9 is used toreceive the fifth control signal EM(n). The second terminal of the lightemitting element L1 is electrically coupled to the second system voltageterminal VSS.

The driving transistor Td is used to provide the driving current to thelight emitting element L1 according to the electric potential of thegate terminal of the driving transistor to drive the light emittingelement L1 to emit light. Furthermore, the ninth transistor T9 isenergized by the fifth control signal EM(n) to conduct theaforementioned driving current of the current path from the first systemvoltage terminal VDD through the driving transistor Td, the ninthtransistor T9, and the light emitting element L1 to the second systemvoltage terminal VSS.

The compensating circuit 140 is electrically coupled between the gateterminal and the second terminal of the driving transistor Td, and thecompensating circuit 140 is used to compensate the critical voltage ofthe driving transistor Td.

The first terminal of the capacitor Cs is electrically coupled to thedriving transistor Td, and the second terminal of the capacitor Cs iselectrically coupled to the voltage stabilizing circuit 150.

The voltage stabilizing circuit 150 is electrically coupled between thesecond terminal of the capacitor Cs and the reference voltage terminalVref, and the voltage stabilizing circuit 150 is used to stabilize theelectric potential of the second terminal of the capacitor Cs.

The writing circuit 160 is electrically coupled to the second terminalof the capacitor Cs, and the writing circuit 160 is used to transmit thedata signal DATA to the second terminal of the capacitor Cs.

Please refer to FIG. 2B, FIG. 2B shows a circuit architecture diagram ofthe driving circuit 100 b in FIG. 2A according to some embodiment of thepresent disclosure.

As shown in Fib. 2B, the reset circuit 110 includes the first transistorT1, the second transistor T2, and the third transistor T3. The sensingcircuit 120 includes the fourth transistorT4. The read circuit 130includes the fifth transistor T5.

The first transistor T1, the second transistor T2, the third transistorT3, the fourth transistorT4, and the fifth transistor T5 of the drivingcircuit 100 b of the FIG. 2B are connected similarly to the firsttransistor T1, the second transistor T2, the third transistor T3, thefourth transistor T4, and the fifth transistor T5 of FIG. 1B,respectively. Therefore, it will not repeat here.

The compensating circuit 140 includes the sixth transistor T6. The firstterminal of the sixth transistor T6 is electrically coupled to thesecond terminal of the driving transistor Td, the second terminal of thesixth transistor T6 is electrically coupled to the gate terminal of thedriving transistor Td, the gate terminal of the sixth transistor T6 isused to receive the third control signal SN(n). Wherein the node N1 isat the connection between the gate terminal of the driving transistor Tdand the second terminal of the sixth transistor T6, and the nodes N2 isat the connection between the second terminal of the driving transistorTd and the first terminal of the sixth transistor T6.

The voltage stabilizing circuit 150 includes the seventh transistor T7.The first terminal of the seventh transistor T7 is electrically coupledto the second terminal of the capacitor Cs, the second terminal of theseventh transistor T7 is electrically coupled to the reference voltageterminal Vref, and the gate terminal of the seventh transistor T7 isused to receive the third control signal SN(n).

The writing circuit 160 includes the eighth transistor T8. The firstterminal of the eighth transistor T8 is electrically coupled to thefirst terminal of the capacitor Cs, the second terminal of the eighthtransistor T8 is configure to receive the data signal DATA, and the gateterminal of the eighth transistor T8 is used to receive the fourthcontrol signal SN(n+1). The node N3 is at the connection between thesecond terminal of the capacitor Cs and the eighth transistor T8.

Please refer to FIG. 3 , FIG. 3 is a timing diagram of the controlsignals of the driving circuit 100 b in FIG. 2B according to anembodiment. As shown in FIG. 3 , the display cycle in the control timingof the driving circuit 100 b can be divided into two phases, which arethe touch sensing phase PT and the display phase PD. The touch sensingphase PT includes the reset period P1, and the sensing period P2. Thedisplay phase PD includes the reset period P3, the compensation periodP4, the writing period P5, and the emitting light period P6. Inparticular, the lengths of the plural periods in FIG. 3 are forillustrative purposes only and are not intended to limit the presentdisclosure.

In detail, the first control signal RST(n) has the first logic level(for example: the low logic level) during the reset period P1, P3; thefirst control signal RST(n) has the second logic level (for example: thehigh logic level) during the sensing period P2, the compensation periodP4, the writing period P5, and the emitting light period P6. The secondcontrol signal SC(n) has the first logic level during the sensing periodP2; the second control signal SC(n) has the second logic level duringthe reset period P1, the reset period P3, the compensation period P4,the writing period P5, and the emitting light period P6. The thirdcontrol signal SN(n) has the first logic level during the compensationperiod P4; the third control signal SN(n) has the second logic levelduring the reset period P1, the sensing period P2, the reset period P3,the writing period P5, and the emitting light period P6. The fourthcontrol signal SN(n+1) has the first logic level during the writingperiod P5; the fourth control signal SN(n+1) has the second logic levelduring the reset period P1, the sensing period P2, the reset period P3,the compensation period P4, and the emitting light period P6. The fifthcontrol signal EM(n) has the first logic level during the emitting lightperiod P6; the fifth control signal EM(n) has the second logic levelduring reset period P1, the sensing period P2, reset period P3, thecompensation period P4, and the writing period P5.

In some embodiment, the first control signal RST(n) is the reset controlsignal, the second control signal SC(n) is the sensing control signal,and the fifth control signal EM(n) is the emitting light control signal.

To make the overall operation of the driving circuit 100 b clearer andeasier to understand, please refer to FIG. 2B, FIG. 3 , and FIGS. 4A to4E together. FIG. 4A is a circuit state diagram of the driving circuitin FIG. 2B during the reset period P1. FIG. 4B is a circuit statediagram of the driving circuit in FIG. 2B during the sensing period P2.FIG. 4C is a circuit state diagram of the driving circuit in FIG. 2Bduring the compensation period P4. FIG. 4D is a circuit state diagram ofthe driving circuit in FIG. 2B during the writing period P5. FIG. 4E isa circuit state diagram of the driving circuit in FIG. 2B during theemitting light period P6.

During reset period P1, the first transistor T1, the second transistorT2, and the third transistor T3 are turn on because the first controlsignal RST(n) has the low logic level. In the other side, the fourthtransistor T4, the fifth transistor T5, the sixth transistor T6, theseventh transistor T7, the eighth transistor T8, and the ninthtransistor T9 are turned off because the second control signal SC(n),the third control signal SN(n), the fourth control signal SN(n+1), andthe fifth control signal EM(n) have the high logic level.

In detail, during the reset period P1, the voltage Vr of the referencevoltage terminal Vref will be transmitted to the second terminal of thecapacitor Cs through the second transistor T2, so that the electricpotential of the second terminal (node N3) of the capacitor Cs issubstantially equal to the voltage Vr. The voltage Vr of the referencevoltage terminal Vref will be transmitted to the node N1 through thefirst transistor T1, so that the electric potential of the gate terminalof the driving transistor Td and the first terminal (node N1) of thecapacitor Cs is substantially equal to the voltage Vr. Also, the voltageVr of the reference voltage terminal Vref will also be transmitted tothe touch sensing electrode TP through the first transistor T1 and thethird transistor T3, so that the electric potential of the touch sensingelectrode TP is substantially equal to the voltage Vr. In this way,during the reset period P1, the electric potential of the gate terminalof the driving transistor Td and the second terminal of the capacitor Cscan be reset and stabilized at the voltage Vr, and the driving circuit100 b completes the reset operation.

During the sensing period P2, the fourth transistor T4 and the fifthtransistor T5 are turned on because the second control signal SC(n) hasthe low logic level. In the other side, the first transistor T1, thesecond transistor T2, the third transistor T3, the sixth transistorT6,the seventh transistorT7, the eighth transistor T8, and the ninthtransistor T9 are turned off because the first control signal RST(n),the third control signal SN(n), the fourth control signal SN(n+1), andthe fifth control signal EM(n) have the high logic level.

In detail, during the sensing period P2, the node N1 will beelectrically isolated from the reference voltage terminal Vref becausethe first transistor T1, the second transistor T2, and the seventhtransistor T7 are switched off. Also, the node N1 will be electricallyisolated from the second system voltage terminal VSS because the eighthtransistor T8 and the ninth transistor T9 are switched off.

When the third control signal SN(n) switches from high level to lowlevel at the beginning of the sensing period P2, the electric potentialof the node N1 is lowered by the parasitic capacitor, and the loweredelectric potential of the node N1 is expressed as the voltage Vft1. Insome embodiment, the voltage Vft1 can be expressed by the followingequation:

Vft1=Cgs*(VGH−VGL)/(Cs+Cgs)  Formula (1)

In the above formula, Cgs can be the parasitic capacitance of theelement of the electrical coupling the node N1 (for example, the fifthtransistor T5), VGH, VGL can be the high electric potential and the lowelectric potential of the third control signal SN(n), respectively, andCs can be the capacitance value of the capacitor Cs.

That is, if the user does not touch the display panel and thus the touchsensing electrode TP is not electrically coupled to the additionalequivalent capacitor, the electric potential of the node N1 will be thevoltage Vr of the reference voltage terminal Vref minus Vft1.

In the other side, if the user's finger touches the display panel, theuser's finger will be treated as (equivalent to) the electrical couplingto the capacitance of the touch sensing electrode TP, and the thirdcontrol signal SN(n) will lower the electric potential of the node N1through the parasitic capacitance when switching from high level to lowlevel at the beginning of the sensing period P2, and the loweredelectric potential of the node N1 is expressed as the voltage Vft2. Insome embodiment, the voltage Vft2 can be expressed by the followingformula:

Vft2=Cgs*(VGH−VGL)/(Cs+Cgs+Cf)  Formula (2)

Similarly, in the above formula, Cgs can be the parasitic capacitance ofthe element of the electrical coupling the node N1 (for example, thefifth transistor T5), VGH, VGL can be the high potential and the lowpotential of the third control signal SN(n), respectively, Cs can beregarded as the capacitance value of the capacitance Cs, and Cf can beregarded as the capacitance value equivalent to the electrical couplingcontact when the user's finger touches the display panel.

That is, if the touch sensor TP is electrically coupled to theadditional equivalent capacitor because the user has touched the displaypanel, the electric potential of the node N1 will be the voltage Vr ofthe reference voltage terminal Vref minus the voltage Vft2.

According to the formula (1) and the formula (2), the value of thevoltage Vft2 will be smaller than the value of the voltage Vft1, and thepotential of the node N1 will be the voltage Vr of the reference voltageVref minus the voltage Vft2 or Vft1, and the electric potential of thenode N1 will be at a higher level when the user has touched the displaypanel compared to when the user has not touched the display panel.

Also, during the sensing period P2, the driving transistor Td providesthe current to the read circuit 130 from the first system voltageterminal VDD according to the electric potential of the gate terminal(node N1) of the driving transistor, so that the read circuit 130 usesthe aforementioned current as the touch sensing signal TS. The electricpotential of the gate terminal of the driving transistor Td will be atthe higher level when the user touches the display panel than when theuser does not touch the display panel, thus providing the smallercurrent for the touch sensing signal TS.

For example, if the user does not touch the display panel, the drivingtransistor Td will provide 27.6 micro amps of current as the touchsensing signal TS. On the other hand, if the user touches the displaypanel, the driving transistor Td will provide the current of 17.3 microamps as the touch sensing signal TS. In this way, during the sensingperiod P2, the driving circuit 100 b completes the touch sensingoperation.

Furthermore, depending on the gap depth of the user's fingerprint, thecapacitance value Cf of the equivalent electrical coupling contact thetouch sensing electrode TP will have different values, and the drivingtransistor Td will provide different amplitude currents as the touchsensing signal TS.

For example, if the user lightly touches the display panel, the largergap between the user's fingerprint and the display panel will cause thecapacitance value Cf to be at the smaller value and the drivingtransistor Td to provide the larger (for example, 26.6 micro amps)current as the touch sensing signal TS. On the other hand, if the usertouches the display panel more closely, a smaller gap between the user'sfingerprint and the display panel will cause the capacitance value Cf tobe at the larger value and the driving transistor Td to provide thesmaller (for example, 18.8 micro amps) current as the touch sensingsignal TS. In this way, during the sensing period P2, the drivingcircuit 100 b can further differentiate between the user's finger andthe display panel in terms of how closely it touches.

Next, in order to reset the electric potential of the driving transistorTd to the voltage Vr of the reference voltage terminal Vref, the resetoperation is performed during the reset period P3.

During the reset period P3, the first transistor T1, the secondtransistor T2, and the third transistor T3 are turned on because thefirst control signal RST(n) has the low logic level. On the other hand,the fourth transistor T4, the fifth transistor T5, the sixth transistorT6, the seventh transistor T7, the eighth transistor T8, and the ninthtransistor T9 are turned off because the second control signal SC(n),the third control signal SN(n), the fourth control signal SN(n+1), andthe fifth control signal EM(n) have the high logic level.

Since the operation of the driving circuit 100 b during the reset periodP3 is similar to the operation of the driving circuit 100 b during thereset period P1, it will not be repeated here.

During the compensation period P4, the sixth transistor T6 will beturned on because the third control signal SN(n) has the low logiclevel. On the other side, the first transistor T1, the second transistorT2, the third transistor T3, the fourth transistor T4, the fifthtransistor T5, the seventh transistor T7, the eighth transistor T8, andthe ninth transistor T9 will be turned off because the first controlsignal RST(n), the second control signal SC(n), the fourth controlsignal SN(n+1), and the fifth control signal EM(n) have the high logiclevel.

In detail, during the compensation period P4, the voltage Vdd of thefirst system voltage terminal VDD is transmitted by the drivingtransistor Td and the sixth transistor T6 to the gate terminal of thedriving transistor Td until the driving transistor Td is cut off. Thatis, when the electric potential difference between the source terminaland the gate terminal of the driving transistor Td is approximately thesame as the critical voltage Vth of the driving transistor Td, thedriving transistor Td cuts off. At this time, the electric potential ofthe first terminal (source terminal) of the driving transistor Td is atthe voltage Vdd, and the electric potential of the gate terminal (nodeN1) of the driving transistor Td is (Vdd−|Vth|). In this way, thedriving circuit 100 b completes the compensation operation during thecompensation period P4.

During the writing period P5, the eighth transistor T8 is turned onbecause the fourth control signal SN(n+1) has the low logic level. Onthe other side, the first transistor T1, the second transistor T2, thethird transistor T3, the fourth transistor T4, the fifth transistor T5,the sixth transistor T6, the seventh transistor T7, and the ninthtransistor T9 are turned off because the first control signal RST(n),the second control signal SC(n), the third control signal SN(n), and thefifth control signal EM(n) have the high logic level.

In detail, during the writing period P5, the voltage Vdata of the datasignal DATA is transmitted from the eighth transistor T8 to the secondterminal of the capacitor Cs, so that the electric potential of thesecond terminal (node N3) of the capacitor Cs is substantially equal tothe voltage Vdata. Furthermore, the electric potential of the secondterminal (node N3) of the capacitor Cs, which changes from thecompensation period P4 to the writing period P5, is transmitted to thefirst terminal (node N1) by capacitive coupling. That is, the voltage(Vdata-Vr) increases at the first terminal (node N1), which means thatthe electric potential at the first terminal (node N1) of the capacitorCs is essentially equal to [Vdd−|Vth|+(Vdata−Vr)]. At this time, theelectric potential of the first terminal (source terminal) of thedriving transistor Td is at the voltage Vdd. The voltage difference(Vsg) across the source terminal and the gate terminal of the drivingtransistor Td is Vdd−[Vdd−|Vth|+(Vdata−Vr)]=[(Vr−Vdata)+|Vth|].

In general, the driving current that the P-type transistor can provideobeys the following formula: Id=k(Vsg−IVth1)² Wherein k is a constantrelated to the component characteristics of the driving transistor Td,and Nth' is the absolute value of the critical voltage of the drivingtransistor Td.

The driving current Id is calculated by substituting the voltage (Vsg)across the source terminal and the gate terminal of the drivingtransistor Td into the equation of the driving current Id as follows:

Id=k(Vsg−|Vth|)²

Id=k{[(Vr−Vdata)+|Vth″]−|Vth|}²

Id=k(Vr−Vdata)²

During the emitting light period P6, the driving transistor Td providesthe driving current Id=k(Vr−Vdata)² to the light emitting element L1, sothat the light emitting element L1 emits light according to theamplitude of the driving current Id.

For example, if the voltage Vdata of the data signal DATA written to thedriving circuit 100 b is larger during the writing period P5, the lightemitting elementL1 will be at the lower brightness (gray scale) based onthe smaller driving current Id during the emitting light period P6according to the aforementioned formula for the driving current Id; onthe other side, if the voltage Vdata of the data signal DATA written tothe driving circuit 100 b is smaller, the light emitting element L1 willbe at the higher brightness (gray scale) based on the larger drivingcurrent Id during the emitting light period P6 according to theaforementioned formula for the driving current Id.

Please refer to FIG. 5 , FIG. 5 is a schematic diagram of the structureof the touch sensing electrode TP in the thin film transistor layer 200in FIG. 2A and FIG. 2B.

As shown in FIG. 5 , the thin film transistor layer 200 includes thesubstrate SUB, the source/drain terminal 210, the gate terminal 220, thepolysilicon layer 230, the dielectric layer 240, the dielectric layer250, the gate dielectric layer 260, the buffer layer 270, and the touchsensing electrode TP. It should be noted that the touch sensingelectrode TP can be set at the position adjacent to the substrate SUB inthe thin film transistor layer 200. More specifically, in the thin filmtransistor layer 200, the touch sensing electrode TP is provided betweenthe buffer layer 270 and the substrate SUB. In this way, in someembodiments, the display panel realized by the driving circuit 100 b canbe the edge-lit light emitting display panel or the back-lit lightemitting display panel.

Please refer to FIG. 6A, FIG. 6A shows a function block diagram of thedriving circuit 100 c according to some embodiment of the presentdisclosure. As shown in FIG. 6A, the driving circuit 100 c includes thetouch sensing electrode TP, the reset circuit 110, the sensing circuit120, the read circuit 130, the capacitor Cs, and the driving transistorTd.

The operation of the touch sensing electrode TP, the reset circuit 110,the sensing circuit 120, the read circuit 130, the capacitor Cs, and thedriving transistor Td of the driving circuit 100 c in FIG. 6A is similarto the operation of the touch sensing electrode TP, the reset circuit110, the sensing circuit 120, the read circuit 130, the capacitor Cs,and the driving transistor Td of the driving circuit 100 b in FIG. 2A,respectively. Therefore, it will not be repeated here.

The driving circuit 100 c further includes the compensating circuit 140,the voltage stabilizing circuit 150, the writing circuit 160, the ninthtransistor T9, the tenth transistor T10, and the light emittingelementL1. In some embodiment, the light emitting element L1 can beimplemented by the micro light emitting diode, the light emitting diode,the mini light emitting diode, or the other light emitting element.

It is important to note that the light emitting element L1 can beimplemented by the light emitting diode (LED) chip. The aforementionedLED chip can be differentiated into the lateral, the flip, and thevertical structures depending on the location of the electrodes. In theembodiment of FIG. 6A, the touch sensing electrode TP of the drivingcircuit 100 c can be implemented by the cathode electrode of the lightemitting element L1 (for example, the light emitting diode chip) in anyof the aforementioned structures, thereby reducing the additionalelectrical surface area of the touch sensor element in otherembodiments.

On the structure, the driving transistor Td, the ninth transistor T9,the light emitting element L1, and the tenth transistor T10 areelectrically coupled between the first system voltage terminal VDD andthe second system voltage terminal VSS. In detail, the first terminal ofthe driving transistor Td is electrically coupled to the first systemvoltage terminal VDD, the second terminal of the driving transistor Tdis electrically coupled to the first terminal of the ninth transistorT9, the second terminal of the ninth transistor T9 is electricallycoupled to the first terminal of the light emitting element L1, and thegate terminal of the ninth transistor T9 is used to receive the fifthcontrol signal EM(n). The second terminal of the light emitting elementL1 is electrically coupled to the first terminal of the tenth transistorT10, and the second terminal of the tenth transistor T10 is electricallycoupled to the second system voltage terminal VSS.

The driving transistor Td is used to provide the driving current to thelight emitting element L1 according to the electric potential of thegate terminal to drive the light emitting element L1 to emit light.Furthermore, the ninth transistor T9 and the tenth transistor T10 areenergized by the fifth control signal EM(n) to conduct theaforementioned driving current of the current path from the first systemvoltage terminal VDD through the driving transistor Td, the ninthtransistor T9, the light emitting element L1, and the tenth transistorT10 to the second system voltage terminal VSS.

The compensating circuit 140 is electrically coupled between the gateterminal (node N1) of the driving transistor Td and the second terminal(node N2), and the compensating circuit 140 is used to compensate thecritical voltage of the driving transistor Td.

The first terminal of the capacitor Cs is electrically coupled to thegate terminal (node N1) of the driving transistor Td, and the secondterminal of the capacitor Cs is electrically coupled to the voltagestabilizing circuit 150.

The voltage stabilizing circuit 150 is electrically coupled between thesecond terminal of the capacitor Cs and the reference voltage terminalVref, and the voltage stabilizing circuit 150 is used to stabilize theelectric potential of the second terminal of the capacitor Cs.

The writing circuit 160 is electrically coupled to the second terminal(node N3) of the capacitor Cs, and the writing circuit 160 is used totransmit the data signal DATA to the second terminal (node N3) of thecapacitor Cs.

Please refer to FIG. 6B, FIG. 6B shows the circuit architecture diagramof the driving circuit 100 c in FIG. 6A according to some embodiment ofthe present disclosure.

As shown in FIG. 6B, the reset circuit 110 includes the first transistorT1, the second transistor T2, and the third transistor T3. The sensingcircuit 120 includes the fourth transistor T4. The read circuit 130includes the fifth transistor T5.

On the structure, compared with the driving circuit 100 b in theembodiment of FIG. 2B, the driving circuit 100 c in the embodiment ofFIG. 6B differs in the connection of the third transistor T3, the fourthtransistor T4, and the touch sensing electrode TP. More precisely, inthe driving circuit 100 c shown in FIG. 6B, the third transistor T3, thetouch sensing electrode TP, and the fourth transistor T4 areelectrically connected in series between the reference voltage terminalVref and the node N1. In the driving circuit 100 b shown in FIG. 2B, thethird transistor T3 and the fourth transistor T4 are connected inparallel and electrically coupled to the touch sensing electrode TP.Although the detailed connection relationships of the driving circuit100 b and 100 c are not identical, the operations of the thirdtransistor T3 and the fourth transistor T4 of the driving circuit 100 cin FIG. 6B are similar to the operations of the third transistor T3 andthe fourth transistor T4 of the driving circuit 100 b in FIG. 2B.Therefore, it will not be repeated here.

The compensating circuit 140 includes the sixth transistor T6, thevoltage stabilizing circuit 150 includes the seventh transistor T7, andthe writing circuit 160 includes the eighth transistor T8. Theconnection relationship and operation method of the sixth transistor T6,the seventh transistor T7, and the eighth transistor T8 of the drivingcircuit 100 c are similar to the connection relationship and theoperation method of the sixth transistor T6, the seventh transistor T7,and the eighth transistor T8 of the driving circuit 100 b in FIG. 2B,respectively. Therefore, it will not be repeated here.

Since the timing diagram of the control signal of the driving circuit100 c can also be implemented by FIG. 3 , please refer to both FIG. 3and FIG. 7A to 7E. FIG. 7A is a circuit state diagram of the drivingcircuit 100 c in FIG. 6B during the reset period P1. FIG. 7B is acircuit state diagram of the driving circuit 100 c in FIG. 6B during thesensing period P2. FIG. 7C is a circuit state diagram of the drivingcircuit 100 c in FIG. 6B during the compensation period P4. FIG. 7D is acircuit state diagram of the driving circuit 100 c in FIG. 6B during thewriting period P5. FIG. 7E is a circuit state diagram of the drivingcircuit 100 c in FIG. 6B during the emitting light period P6. As shownin FIG. 3 and FIGS. 7A to 7E, the driving circuit 100 c operates in thesimilar manner to the driving circuit 100 c. Therefore, it will not berepeated here.

Please refer in FIG. 8 , FIG. 8 is a waveform diagram of the controlsignal of the driving circuit 100 c and the current flowing through thedriving transistor in FIG. 6B and the waveforms of current Id0 to Id8flowing through the driving transistor Td according to different touchlevels. As shown in FIG. 8 , the first control signal RST(n) has the lowlogic during the reset period P1 and P3; the second control signal SC(n)has the low logic during the sensing period P2; the third control signalSN(n) has the low logic level during the compensation period P4; thefourth control signal SN(n+1) has the low logic during the writingperiod P5; the fifth control signal EM(n) has the low logic during theemitting light period P6.

In some embodiment, during the sensing period P2, depending on the depthof the gap between the user's fingerprints, the capacitance value Cf ofthe equivalent electrical coupling the touch sensing electrode TP willhave different values, and the driving transistor Td will providedifferent amplitude currents as the touch sensing signal TS. Forexample, if the user lightly touches the display panel, the large gapbetween the user's fingerprint and the display panel will cause thecapacitance value Cf to be at a smaller value and the driving transistorTd to provide the larger current Id1, 27.1 micro amps, as the touchsensing signal TS. On the other side, if the user touches the displaypanel more closely, the gap between the user's fingerprints and thedisplay panel is smaller, which will cause the capacitance value Cf tobe at the larger value and the driving transistor Td to provide thesmaller current Id8, 17.2 micro amps, as the touch sensing signal TS. Inthe embodiment shown in FIG. 8 , the currents Id0 to Id8 are 27.6, 27.1,26.6, 25.2, 23.4, 21.0, 18.8, 17.8, and 17.2 micro amperes,respectively. Also, the values of currents Id0-Id8 are 118.7 mA duringthe emitting light period P6. In other words, even if the touch sensingelectrode TP is realized by the cathode of the light emitting elementL1, the user's touch will not affect the magnitude of the drivingcurrent provided to the light emitting element L1 during the emittinglight period P6. In this way, during the sensing period P2, the drivingcircuit 100 c can further differentiate between the user's finger andthe display panel in terms of how closely it touches.

In summary, the driving circuit 100 a, 100 b, and 100 c of the presentdisclosure use the touch sensing electrode TP to sense the user's touch,and the sensing circuit 120 transmits the electric potential of thetouch sensing electrode TP to the gate terminal of the drivingtransistor Td, and the read circuit 130 outputs the touch sensing signalTS according to the electric potential of the gate terminal of thedriving transistor Td, so that the driving circuit 100 a, the 100 b, and100 c can integrate the touch sensor function and the pixel drivingcircuit, and the display time will not be reduced due to the bitresolution and frame rate. Furthermore, the touch sensing electrode TPof the driving circuit 100 b can be set at the specific position in thethin film transistor layer 200 to realize the edge-lit light emittingdisplay panel or the back-lit light emitting display panel. On the otherside, the touch sensing electrode TP of the driving circuit 100 c can beimplemented by the cathode electrode of the light emitting element L1,thereby reducing the area of the touch sensor.

Although the present invention has been described in considerable detailwith reference to certain embodiments thereof, other embodiments arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the embodiments contained herein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims.

1. A driving circuit, comprising: a driving transistor; a capacitor,electrically coupled to a gate terminal of the driving transistor; areset circuit, electrically coupled to the gate terminal of the drivingtransistor, and configured to reset an electric potential of the gateterminal of the driving transistor; a touch sensing electrode; a sensingcircuit, electrically coupled between the touch sensing electrode andthe gate terminal of the driving transistor, wherein the sensing circuitis configured to change the electric potential of the gate terminal ofthe driving transistor according to a capacitance variation related tothe touch sensing electrode; and a read circuit, wherein the readcircuit is electrically coupled to the driving transistor, and the readcircuit is configured to transmit a touch sensing signal according tothe electric potential of the gate terminal of the driving transistor.2. The driving circuit of claim 1, wherein the reset circuit comprises:a first transistor, wherein a first terminal of the first transistor iselectrically coupled to the gate terminal of the driving transistor anda first terminal of the capacitor, a second terminal of the firsttransistor is electrically coupled to a reference voltage terminal, anda gate terminal of the first transistor is configured to receive a firstcontrol signal; and a second transistor, wherein a first terminal of thesecond transistor is electrically coupled to a second terminal of thecapacitor, a second terminal of the second transistor is electricallycoupled to the reference voltage terminal, and a gate terminal of thesecond transistor is configured to receive the first control signal. 3.The driving circuit of claim 2, wherein when the first control signalhas a first logic level, the first transistor transmits the electricpotential of the reference voltage terminal to the gate terminal of thedriving transistor through the first transistor to reset the electricpotential of the gate terminal of the driving transistor, and the secondtransistor is turned on so that the electric potential of the referencevoltage terminal is transmitted to the second terminal of the capacitorthrough the second transistor.
 4. The driving circuit of claim 2,wherein the reset circuit is further configured to reset the electricpotential of the touch sensing electrode, and the reset circuit furthercomprises: a third transistor, wherein a first terminal of the thirdtransistor is electrically coupled to the touch sensing electrode, asecond terminal of the third transistor is electrically coupled to thegate terminal of the driving transistor, and a gate terminal of thethird transistor is configured to receive the first control signal. 5.The driving circuit of claim 2, wherein the reset circuit is furtherconfigured to reset the electric potential of the touch sensingelectrode, and the reset circuit further comprises: a third transistor,wherein a first terminal of the third transistor is electrically coupledto the reference voltage terminal, a second terminal of the thirdtransistor is electrically coupled to the touch sensing electrode, and agate terminal of the third transistor is configured to receive the firstcontrol signal.
 6. The driving circuit of claim 1, wherein the sensingcircuit comprises: a fourth transistor, wherein a first terminal of thefourth transistor is electrically coupled to the touch sensingelectrode, a second terminal of the fourth is electrically coupled tothe gate terminal of the driving transistor, and a gate terminal of thefourth transistor is configured to receive a second control signal;wherein when the second control signal has a first logic level, thefourth transistor is turned on so that the electric potential of thetouch sensing electrode is transmitted to the gate terminal of thedriving transistor through the fourth transistor.
 7. The driving circuitof claim 1, wherein a first terminal of the driving transistor iselectrically coupled to a first system voltage terminal, and a secondterminal of the driving transistor is electrically coupled to the readcircuit, wherein the read circuit comprises: a fifth transistor, whereina first terminal of the fifth transistor is electrically coupled to thesecond terminal of the driving transistor, a second terminal of thefifth transistor is configured to output the touch sensing signal, and agate terminal of the fifth transistor is configured to receive a secondcontrol signal; wherein when the second control signal has a first logiclevel, the fifth transistor is turned on, and the fifth transistoroutputs the touch sensing signal according to the electric potential ofthe gate terminal of the driving transistor.
 8. The driving circuit ofclaim 1, further comprising: a light emitting element, wherein thedriving transistor is configured to drive the light emitting element,and the light emitting element and the driving transistor areelectrically coupled between a first system voltage terminal and asecond system voltage terminal.
 9. The driving circuit of claim 8,wherein a first terminal of the capacitor is electrically coupled to thegate terminal of the driving transistor, and a first terminal of thedriving transistor is electrically coupled to the first system voltageterminal, wherein the driving circuit further comprises: a compensatingcircuit, electrically coupled between the gate terminal of the drivingtransistor and a second terminal of the driving transistor; a voltagestabilizing circuit, electrically coupled to a second terminal of thecapacitor, and configured to stabilize the electric potential of thesecond terminal of the capacitor; and a writing circuit, electricallycoupled to the second terminal of the capacitor, and configured totransmit a data signal to the second terminal of the capacitor.
 10. Thedriving circuit of claim 9, wherein the compensating circuit comprises:a sixth transistor, wherein a first terminal of the sixth transistor iselectrically coupled to the second terminal of the driving transistor, asecond terminal of the sixth transistor is electrically coupled to thegate terminal of the driving transistor, and a gate terminal of thesixth transistor is configured to receive a third control signal. 11.The driving circuit of claim 10, wherein the voltage stabilizing circuitcomprises: a seventh transistor, wherein a first terminal of the seventhtransistor is electrically coupled to the second terminal of thecapacitor, a second terminal of the seventh transistor is electricallycoupled to a reference voltage terminal, and a gate terminal of theseventh transistor is configured to receive the third control signal.12. The driving circuit of claim 11, wherein when the third controlsignal has a first logic level, the sixth transistor is turned on sothat an electric potential of the first system voltage terminal istransmitted to the gate terminal of the driving transistor through thedriving transistor and the sixth transistor until the driving transistoris turned off, and the seventh transistor is turned on so that anelectric potential of the reference voltage terminal is transmitted tothe second terminal of the capacitor through the seventh transistor tostabilize the electric potential of the second terminal of thecapacitor.
 13. The driving circuit of claim 9, wherein the writingcircuit comprises: an eighth transistor, wherein a first terminal of theeighth transistor is electrically coupled to the second terminal of thecapacitor, a second terminal of the eighth transistor is configured toreceive the data signal, and a gate terminal of the eighth transistor isconfigured to receive a fourth control signal; wherein when the fourthcontrol signal has a first logic level, the eighth transistor is turnedon so that the data signal is transmitted to the second terminal of thecapacitor through the eighth transistor.
 14. The driving circuit ofclaim 9, further comprising: a ninth transistor, wherein a firstterminal of the ninth transistor is electrically coupled to the secondterminal of the driving transistor, a second terminal of the ninthtransistor is electrically coupled to a first terminal of the lightemitting element, and a gate terminal of the ninth transistor isconfigured to receive a fifth control signal; wherein when the fifthcontrol signal has a first logic level, the ninth transistor is turnedon so that the light emitting element emits light according to theelectric potential of the gate terminal of the driving transistor. 15.The driving circuit of claim 9, further comprising: a ninth transistor,wherein a first terminal of the ninth transistor is electrically coupledto the second terminal of the driving transistor, a second terminal ofthe ninth transistor is electrically coupled to a first terminal of thelight emitting element, and a gate terminal of the ninth transistor isconfigured to receive a fifth control signal; and a tenth transistor,wherein a first terminal of the tenth transistor is electrically coupledto the second terminal of the light emitting element, a second terminalof the tenth transistor is electrically coupled to the second systemvoltage terminal, and a gate terminal of the tenth transistor isconfigured to receive the fifth control signal; wherein when the fifthcontrol signal has a first logic level, the ninth transistor and thetenth transistor are turned on so that the light emitting element emitslight according to the electric potential of the gate terminal of thedriving transistor.
 16. The driving circuit of claim wherein the touchsensing electrode is a cathode electrode of the light emitting element.17. The driving circuit of claim 1, wherein the touch sensing electrodeis adjacent to a basal layer in a thin film transistor layer.
 18. Thedriving circuit of claim 17, wherein a display panel realized by thedriving transistor is an edge-lit light emitting display panel or aback-lit light emitting display panel.